The present invention relates generally to abrasive articles for abrading a work surface such as, for example, flexible sheet-like abrasive articles.
Sheet-like abrasive articles are commonly used in a variety of sanding operations including, for example, hand sanding of wooden surfaces. In hand sanding, the user holds the abrasive article directly in his or her hand and moves the abrasive article across the work surface. Sanding by hand can, of course, be an arduous task.
Sheet-like abrasive articles include, for example, conventional sandpaper. Conventional sandpaper is typically produced by affixing abrasive material to a relatively thin, generally non-extensible, non-resilient, non-porous backing (e.g., paper). The thin, flat, slippery nature of conventional sandpaper backing materials makes conventional sandpaper difficult to grasp, hold, and maneuver. Because of the slippery nature of conventional sandpaper, to hold a sheet of sandpaper securely, a user will grasp the sheet of sandpaper between his or her thumb and one or more of his or her remaining fingers. Holding the sandpaper in this manner is uncomfortable, can lead to muscle cramps and fatigue, and is difficult to maintain for an extended period of time. In addition, the thumb is typically in contact with the abrasive surface of the sandpaper, which can irritate or damage the skin. Also, because the thumb is positioned between the sandpaper and the work surface, grasping the sandpaper in this manner also interferes with the sanding operation. That is, due to the position of the thumb, a portion of the sandpaper abrasive surface is lifted away from the work surface during sanding. Because the lifted portion is not in contact with the work surface, the full sanding surface of the sandpaper is not utilized, and the effectiveness of the sandpaper is, therefore, diminished.
During hand sanding, a user often applies pressure to the sandpaper using his or her fingertips. Because of the thin nature of the backing materials used in conventional sandpaper, the finger pressure is concentrated in the regions where the finger pressure is applied. This, in turn, causes the sandpaper to wear and/or load unevenly, and produces an uneven sanding pattern on the work surface.
Conventional sandpaper is typically sold in standard size sheets, such as 9×11 inch sheets. To make sandpaper easier to use, users often fold the sandpaper, thereby producing smaller sheets that are easier to handle. Folding the sandpaper, however, produces a jagged edge, and also weakens the sandpaper along the fold line. During the rigors of sanding, the weakened fold line may tear, thereby resulting in premature failure of the sandpaper.
Various attempts have been made to provide abrasive articles that make hand sanding easier and/or more comfortable. U.S. Design Pat. No. Des. 372,111 (Zeigler), for example, discloses a combined glove and sandpaper. U.S. Design Pat. No. Des. 526,180 (Holden) discloses a sandpaper glove. Other attempts to produce abrasive articles that are more comfortable are disclosed in U.S. Pat. No. 6,613,113 (Minick et al.), U.S. Pat. No. 7,285,146 (Petersen),U.S. Pat. No. 7,235,114 (Minick et al.), and U.S. Patent Publication 2007/0243802 (Petersen et al.), each of which is assigned to the same assignee as the present invention.
U.S. Pat. No. 3,813,231 (Gilbert et. al.) discloses a flexible abrasive sheet including a backing of a copolymer of ethylene and acrylic acid having a melt index as determined by ASTM Test No. D1238-57T of from about 10 up to about 50 and contains from about 15 up to about 20 percent polymerized acrylic acid based on the weight of the copolymer, and an abrasive grit partially embedded in the ethylene-acrylic acid copolymer backing.
U.S. Pat. No. 4,240,807 (Kronzer) discloses a backing material for use in fabricating flexible abrasive sheets. The backing material comprises a flexible web substrate preferably of tough impregnated paper, having on one surface a heat-activatable binder coating which is a non-tacky solid at ambient temperatures and which coating when heated to a temperature insufficient to thermally degrade the substrate is softened and converted to a viscous fluid condition so that when abrasive grit is deposited on the softened coating and electrostatically aligned, the grit by virtue of its weight alone, i.e., by gravity, will sink into the coating to a depth which provides a firm bond with the coating after the heat is removed and the coating resets to its solid non-tacky state.